The main reason why I share my experience on google maps is that I really love to eat delicious food (or just eat :)) during my travels with my wife. Sometimes it is really hard to find place, where you can eat well. Google makes life much easier, and sharing with other people help me feel, that I make life a little bit better. Without good food any travel may become a complete disappointment.
Another reason is accommodation. Some places are hell on earth and as many people know about it the better I can sleep at night. :)))